5548 ARP Timeout/ Switch Mode

Hi,

In our production environment we are having intermittent connectivity and slowness across all subnets within our layer 2 network. Everything appears to be find from a hardware stand point. Eventually the issue resolves itself. This has led me to believe that there is something going on with the ARP table and MAC address tables. After doing some research most recommend setting the timeout for both to the same (around 300 seconds). Based on what I found in Dell's PC5548 documentation (Dell PowerConnect 5500 Series CLI Reference Guide) the switch needs to be in switch mode (default is router mode) in order to configure the arp timeout to 300 seconds. Below is an excerpt detailing CLI configuration. 

Syntax
arp timeout seconds
no arp timeout

Parameters
seconds—Specifies the time interval (in seconds) during which an entry
remains in the ARP cache.
(Range: 1–40000000)

Default Configuration
The default ARP timeout is 60000 seconds in Router mode, and 300 seconds
in Switch mode.

Command Mode
Global Configuration mode

Example
The following example configures the ARP timeout to 12000 seconds.
Console(config)# arp timeout 12000

How can I change the 5548 to switch mode? How does changing it to switch mode affect the configurations? 

thanks,

Leo